Which element would most likely have chemical properties similar to that of magnesiun

What is the molar mass of a gas that has density of 2.054 g/l

When hydrochloric acid reacts with potassium hydroxide solution, the following reaction occurs. hcl (aq) + koh (aq) h2o (l) + kcl (aq) the reaction gives off heat energy, so it is an reaction.

Connect the whole numbers on the periodic table to indicate what they represent?